The present invention relates to a balancer device of an engine which comprises an oil pump unit driven by a rotation of the engine and a balancer unit.
Such a balancer device of an engine equipped with an oil pump unit and a balancer unit which are coupled to each other and stored inside an oil pan of the engine is known as prior art.
A conventional balancer device disclosed in U.S. Pat. No. 7,905,212 will be described.
In the balancer device of the above-described patent document, this balancer unit comprises a pair of balancer shafts. These balancer shafts are driven by a rotation of the engine. The oil pump unit is driven by a rotation of the balancer shaft. The pump chamber of the oil pump unit is arranged on the side of one of the pair of balancer shafts which are located vehicle-rearward. The oil strainer is arranged in front of the shaft center of the other balancer shaft which is located vehicle-forward. The inlet chamber and the outlet chamber of the oil pump unit are positioned to overlap vertically on one side of the pump chamber in its peripheral direction and to extend linearly vehicle-forward from the pump chamber. Thereby, the inlet and outlet chambers of the oil pump unit which are respectively arranged in front and back of the pump rotor can provide a little-curved structure and a smaller layout space, so that both the discharge function of the oil pump unit and the installment function of the balancer device to the engine can be improved. Further, since the oil pump unit and the balancer unit are coupled to each other, the longitudinal length of the balancer device can be shortened and thereby the size of the balancer device can be properly small.
In case the oil pump unit and the balancer unit are coupled to each other like the device of the above-described patent document, there is a concern that when the oil with a high pressure flows into the balancer unit at the coupling portion from the side of the oil pump unit, the reliability of the balancer shafts may deteriorate. Specifically, the oil inside the oil pump unit does not flow down through any oil filter. Accordingly, dusts and the like (i.e., foreign matters) to damage the balancer shafts and the like may be contained in the flowing oil, so that the balancer shafts may be damaged.